Outdoor spas, hot tubs and the like require piping to carry the water circulating to and from the spa or hot tub and the heater in a circulating loop system. Typically, the pipe is formed of extruded plastic. Where the ambient temperature varies considerably and particularly where the temperature drops below freezing, it is necessary to thermally insulate the pipe within which the water circulates.
In the utilization of the thermal insulated pipes, the heat loss of the pipe to the spa support equipment is materially reduced. Further in the areas where winter weather with sustained below freezing temperature occurs, damage to the plumbing by freezing is likely, however, the utilization of insulated pipe significantly reduces the risk of such damage.
Insulated pipes have been built using a large diameter pipe concentrically surrounding a smaller diameter pipe which carries water and wherein a suitable thermal insulation fills the annular gap between the concentric pipes. Polyurethane foam constitutes one of the best insulation materials for insulating the internal pipe. It is known to foam in the insulation between the concentric, radially spaced pipes with the foam applied in situ.
The problem occurs in the assembly of sections of such insulated pipe, end to end, or the assembly on the job site of one end of the pipe to an appropriate fitting such as a an Ell.
Typically custom spa insulations were either installed without any insulation on the plumbing or a rubber type pipe insulation was employed. Subject to weather and open to the ambient, rain and ultraviolet rays of the sun deteriorate significantly the value of the insulation over a relatively short time span.
Therefore a primary object of the present invention is to provide an improved double sealed insulated spa pipe coupling between two thermally insulated double wall spa pipes as well as a coupling between one end of such thermally insulated double wall pipe and a fitting such as an Ell or the like, in which the end of the inner of two concentric plastic pipe sections may be adhesively sealed to the inner pipe or tube of the next pipe section or Ell, and adhesive coupling then effected between radially enlarged sections of the outer pipe or tube portions of either two double wall insulated spa pipes, or one end of the insulated, double wall insulated spa pipe, and an Ell.